<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        body{
            height: 2500px;
        }
         header{
            height: 60px;
            background-image: url(img/bg4.png);
            background-repeat: repeat-x;
        }
        .box{
            border:40px solid rgba(10,10,10,0.4);
            padding:40px;
            /* background-color: violet;
            background-image: url("/img/2.jpg");
            background-repeat: no-repeat; */
            /* background-position: right top; */
            
            /* 三种写法 */
            /* 
            1，长度标识
            2.百分比
            3.英文字母
            */
            /* background-attachment: fixed; 
            background-size: cover;
            background-position: left top; */
         
            /* background-clip:content-box ; */
            /* background-clip:padding-box ;
            /* 背景显示的起点 */
            /* background-origin: content-box; */
            /* 背景显示的区域 */
            /* background-clip:border-box; */
            background: no-repeat violet   left top/ cover url("/img/2.jpg");
            width: 800px;
            height: 400px;
        }
       
    </style>
</head>
<body>
    <header>

    </header>
    <div class="box">

    </div>
</body>
</html>